Carl Dong d5a71e9785 guix: Use --cores instead of --max-jobs ... In Guix, there are two flags for controlling parallelism: Note: When I say "derivation," think "package" --cores=n - controls the number of CPU cores to build each derivation. This is the value passed to `make`'s `--jobs=` flag. - defaults to 0: as many cores as is available --max-jobs=n - controls how many derivations can be built in parallel - defaults to 1 Therefore, if set --max-jobs=$MAX_JOBS and don't set --cores, Guix could theoretically spin up $MAX_JOBS * $(nproc) number of threads, and that's no good. So we could either default to --cores=1, --max-jobs=$MAX_JOBS - Pro: --cores=1 means that `make` will be invoked with `-j1`, avoiding problems with package whose build systems and test suites break when running multi-threaded. - Con: There will be times when only 1 or 2 derivations can be built at a time, because the rest of the dependency graph all depend on those 1 or 2 derivations. During these times, the machine will be severely under-utilized. or --cores=$MAX_JOBS, --max-jobs=1 - Pro: We don't encounter prolonged periods of severe under-utilization mentioned above. - Con: Many packages' build systems and test suites break when running multi-threaded. or --cores=1, --max-jobs=1 and let the user override with $ADDITIONAL_GUIX_COMMON_FLAGS		2021-04-01 16:53:17 -04:00
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build.sh	guix: Use --cores instead of --max-jobs	2021-04-01 16:53:17 -04:00